In the past, there has been proposed an oral hygiene device capable of preventing occurrence of alveolar pyorrhea and gingival inflammation by improving metabolism and a blood circulation of soft tissues surrounding the oral cavity. Thereby the oral hygiene device can improve oral hygiene.
For example, there has bee proposed an electronic toothbrush (ionic toothbrush) as a one type of the oral hygiene device (see Japanese Patent Publication No. 2560162). The electronic toothbrush weakens adherence developed between a tooth plane and dental plaque by flowing a weak current into the oral cavity (flowing an electrical current between the electronic toothbrush and teeth). Therefore, use of the electronic toothbrush is capable of removing the dental plaque.
The electronic toothbrush disclosed in the aforementioned Japanese patent publication includes a spindle connected to a negative pole of a power source and a terminal member connected to a positive pole in order to flow the weak current into the oral cavity. The terminal member is located on a handle. The spindle is exposed through an exposure groove in a neck. Liquid (e.g. saliva and solution of a dentifrice) in the oral cavity comes into contact with the spindle through the exposure groove during brushing of teeth. Thereby, electrical current flows between the spindle and the terminal member via user's body (the electrical current flows into the oral cavity).
However, in the above electronic toothbrush, the spindle is exposed through the exposure groove formed in the neck. Therefore, depending on an orientation of the electronic toothbrush during brushing of teeth, the liquid may be prevented from flowing into the exposure groove due to gravity acting on the brush. In this instance, the electronic toothbrush fails to flow the current into the oral cavity with a consequence of not achieving an effect of easily removing the dental plaque.